Scaling integrated circuit structures such as device structures and interconnect structures may be limited by the capability of lithography techniques to reliably resolve such transistor and interconnect structures. In some implementations, extreme ultraviolet (EUV) lithography may be used to pattern (e.g., via a resist layer) such structures. However, EUV lithography may have low throughput due to low power sources used for generating EUV photons. One solution is to provide resist (e.g., photoresist) with a higher photospeed (e.g., such that the resist may be patterned at lower power). However such resists tend to have poor pattern fidelity due to shot noise (e.g., low fidelity due to fewer photons doing the work of patterning the resist).
In other implementations, multiple patterning techniques such as multi-pass patterning techniques may be used to provide smaller pattern structures. Such techniques may include dual tone resist techniques, double exposure of the same resist layer, double expose/double etch techniques, or multi-pass patterning techniques using an underlying grating. For example, multi-pass patterning techniques using an underlying grating pattern may include forming a grating pattern and forming a second pattern layer over the grating pattern. Such multi-pass patterning techniques using an underlying grating pattern may rely on scumming to anchor the second pattern layer within the grating pattern for example. For example, some integration schemes based on 193 nanometer (nm) lithography and multi-pass patterning may rely on gratings that are cut or blocked by planarizing multi-layer stacks to generate a final pattern of interest. Such techniques may suffer from low pattern fidelity and a small process window (e.g., depth of focus, exposure latitude, etc.) and pattern placement errors that make alignment to the underlying grating difficult and cost-prohibitive.
As such, there is a continual effort to achieve smaller pattern features with high fidelity, repeatability, and manufacturing tolerances that allow effective low cost manufacturing. Such efforts may become critical as smaller feature sizes are desired.